This invention relates to methods of making developer compositions. More particularly, this invention relates to methods for making two-component electrostatographic developer compositions.
Methods of making developer compositions are known in the art. Reference is made, for example, to U.S. Pat. No. 4,678,734 to Laing et al., which discloses a process for making developer compositions comprising (1) providing carrier particles having a core with a coating thereover; (2) introducing the carrier particles into a blending apparatus; (3) adding to the blending apparatus fine toner particles with a diameter of from about 2 microns to about 10 microns, said particles being comprised of toner resin particles, pigment particles, and a charge enhancing additive; (4) effecting blending for a period of time sufficient to enable the classified toner particles to alter the tribogenerating ability of the surface of the carrier particles and become embedded therein; (5) subsequently adding to the resulting blended mixture toner particles of a diameter of from about 2 to about 18 microns, and comprised of toner resin, pigment particles, and a charge enhancing additive; and (6) blending for a period of from about 1 minute to about 5 minutes.
Although the Laing et al. method produces a developer having relatively stable electrical properties, including consistent triboelectric charging values, acceptable charge distributions, and constant conductivity characteristics, it is desirable to provide a method for making a developer which not only provides developers with stable electrical properties but also with improved machine performance.
Typically, after their introduction into a printing apparatus, developers prepared according to known processes require approximately 21/2 hours of use before they produce prints having high copy quality, e.g., good image sharpness and substantially no background deposits. Furthermore, developers prepared according to known processes generally require production of a high number of copies, e.g., about 2000 copies, before high quality copies are produced.